Robin Williams made Ben Affleck and Matt Damon household names when he decided to star in Good Will Hunting — and Damon says they are forever heartbroken that they never had the chance to fully repay the late actor for “changing the trajectory of our careers completely.”

“A lot of Robin Williams memories, a lot of really good memories of him,” he said. “Ben said recently, ‘It’s weird, we always felt like we had this incredible debt to pay him back. We thought there would be time to do that [but then] the abruptness of somebody leaving like that, and that realization comes that you’re never going to pay back this incredible thing that somebody did for you.”

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“That movie got made because Robin Williams said he wanted to do it. That changes the trajectory of our careers completely — forever,” he added.

Williams died by suicide in August 2014 at age 63. His role in Good Will Hunting, which was released in December 1997, launched childhood friends Damon and Affleck into stardom and earned the Boston natives their first Academy Awards.

Damon also spoke to Seacrest about this year’s Golden Globe-nominated film Manchester by the Sea, which he was initially scheduled to direct. The film was ultimately helmed by Kenneth Lonergan and stars Ben’s little brother Casey Affleck, an actor Damon affectionately noted he’s known since the younger Affleck “was 5.”